Thread rolling apparatus and control means therefor



E. F. w. MOELTZNER ETAL 2,953,953

3 Sheets-Sheet 1 mw 5 .ww mm 9. 8. 6 mm 1 Sept. 27, 1960 THREAD ROLLINGAPPARATUS AND CONTROL MEANS THEREFOR Filed Aug. 4, 1953 INVENTORSATTORNEY/7 p 1960 E. F. w. MOELTZNER EIAL 2,953,953

THREAD ROLLING APPARATUS AND CONTROL MEANS THEREFOR Mn; a mm. n N 0 S 1"I s L t s y W J W W 3 1 v 5 m g Y B 3 5 9 1 4 L. H A d e l 1 FATTORNEKF Sept. 27, 1960 E. F. w. MOELTZNER ErAL 2,953,953

THREAD ROLLING APPARATUS AND CONTROL MEANS THEREFOR Filed Aug. 4, 1953 3Sheets-Sha et 3 INVENTORS [RA/6r FTP/r2 Mann Minn/u ATTORNEKT THREADROLLING APPARATUS AND CONTROL MEANS THEREFOR iaiented se i. 27, 19

after only half :a revolution of the threading rolls, for example. Therolling path of the threading rolls can be changed merely by changingthe speed of the trans mission,' so that, for example, a work piece canbe 5 finish-rolled in 5,43, 4, 1.2 etc. revolutions whereupon ErnstFritz Wilhelm Moeltzner, Berlin-Charlottenburg,

and Johann Hiibl, Berlin-Halensee, Germany, assignors, by mesneassignments, to Landis Machine Company, 'Waynesboro, Pa., a corporationof Pennsylvania Filed Aug. 4, 1953, Ser. No. 372,284

Claims. .(Cl. 80-6) The invention concerns a controlmeans forhydraulically operated thread rolling machines with automatic approachand separation of the threading rolls and more particularly toimprovements in apparatus of the type disclosed incopending'applicationserial No. 365,048 filed June 30, 1953 for RollingMachines and Control Means Therefor now Patent No. 2,873,634 issuedFebruary 17, 1959. In accordance with the aforesaid application SerialNo. 365,048 it has been proposed to reconnect the hydraulic medium,after it has been discon nected by a timer mechanism, by means of acontrollable timing piston, which actuates, after a predetermined time,

a starting switch for the electrical operation of the valve It hasbecome apparent that it is highly advantageous v V to be able readily toadapt the automatic control of thread rolling machines to specificrequirements which arise When'rolling various work pieces. By adjustingthe timer mechanism and the rest interval timing piston, this ispossible only imperfectly and with a great deal of bother. Thus, forexample, it is advantageous to accomplish rapidly the idle travel of thethreading roll, which is dependent upon the distance between the rollsafter they have been separated, in order to reduce the idle time forfeeding large work pieces. Again, small work pieces, of which several,for example, are rolled in one revolution of the rolls, require a rapidreciprocation of the roll. Furthermore, it is important to the rollingprocess that the rolling travel necessary to completely roll the profileto be produced be strictly adhered to.

Heretofore, the timer mechanism was used tto disconnect the rollingpressure and this timer operated to disconnect the rolling pressureafter the expiration of a predetermined time. In the case of shortrolling times which occupy a fraction of one rotation of the threadingrolls, the timer mechanism no longer operates with the requiredaccuracy, since it is not practical to set a rolling time of less thantwo seconds. Therefore, new ways must be found to enable the mostdiverse rolling travels to be infinitely adjusted. These requirementsare fulfilled by the invention, by reason of the fact that one or morevalves, installed in the hydraulic circuit of the cylinder for operatingthe threading rolls, can be operated by the threading roll drive througha variable speed transmission and the length of the rolling path oncylindrical threading rolls can be infinitely adjusted by changing thethreading rolls areseparated, the new work piece is transferred and thethreading rolls approach each other for the new rolling operation.However, the transmission'canbe-adjusted'so'that it actuates two,'threeor more reciprocations of the threading rolls in each revolution of therolls, for example, when, respectively, two, three or more work pieces,for example screws with an M2'or -M1 thread, are to be finish-rolled perrevolution of the threading rolls. The speed ratio set at thetransmission for the speed of the threading rolls controls the length ofthe rolling path. This ratio does not change when the rotational speedof the threading rolls is changed so that it is not necessary, in suchcase, to readjust the transmission. Furthermore, the advantage isobtained that special threading rolls, employed heretofore, havingrecesses for transferring work pieces and having spirally risingsurfaces, are superfluous and are replaced by standard cylindricalthreading rolls. Consequently the adaptability to various rollingprocesses no longer depends on the particular construction of thesespecial threading rolls, which are different for each purpose, but onthe easily operated control means for the automatic reciprocation ofcylindrical rolls.

An advantageous embodiment is one in which two valves are operated insynchronism by the transmission; one of the valves controls the rapidinfeed of the threading rolls and the other controls the reciprocationof the rolls'without rapid infeed. Thereby the advantage is obtainedthat the threading roll can either'be advanced at a rapid rate to thework piece between the rolls, then rolling the work piece or can becontrolled to reciprocate, so that the previous idle time islowered andthe output of the machine is considerably increased. I a

It is advantageous if one of the valve spools, which is .installed inthe hydraulic pressure line, opens, in'its original position, thehydraulic fluid line which leads to theloperating cylinder and which ismetered by a feed regulating .valve and said valve spool, whendisplaced, quickly opens the 'unmetered full cross-sectional area of thepressure line for the rapid in feed and then closes it again,reconnecting the metered line. The other valve, installed in thedischarge line, is closed andfat the end of the rolling operation forthe'first time opens the full cross-sectional area of the discharge linearid then closes it again. The reciprocation of the threading roll maybe adapted to any rolling process by the syn chronized cooperation'ofboth valves. Furthermore, the advantage is obtained that the threadrolling machine opj erates smoothly 'in spite of the rapid infeed,sincethe beginning of the approach movement of the threading roll iseffected by an initially metered hydraulic circuit and the fullcross-sectional area of the hydraulic fluid'line is effective only afterthe start of the approach movement of'the roll.

- An especially suitable embodiment of the-control means, for threadrolling machines is one in which the transmission operates two valvespools with cams mounted at their ends, which are engaged by the pushrods of the spring pressed valve spools. But it is also possible toconstruct both valve spools as rotary valves and to drive them directly-from1tl1e transmission; i

A practical construction is one inwhich ;a stop. cock is installed inthe hydraulic line leading to. ,the--l '-alve for the rapidinfeedcontrol and ahead pftthe,junctiop of the line leadingto the feedregulatingvalve, ,a seeppd stop cock is installed in the line leadingfrom the said valve spool to the operating cylinders and a third stopcock is installed in the discharge line ahead of the other valve spool.The arrangement of these cocks makes it possible to disconnect the valvecontrolling the rapid infeed, simply by closing the cocks and to operatemerely with the valve disposed in the discharge line, which thencontrols the rapid reciprocation of the threading rolls. Furthermore, acomparatively simple system of pressure and discharge lines is possible,so that the control means can be applied as an auxiliary control meansto the standard machine control which is by means of the main controlbox.

For this purpose it is to advantage that the discharge line from theoperating cylinder consists of two lines, one of which leads through themain control valve and the other through one or both valves, and thatthe hydraulic line has a by-pass line ahead of the stop cock and leadingto the operating cylinders, so that the hydraulic circuit of the controlvalves lies parallel to the circuit of the main control valve and themain or secondary control valves may be connected as desired. Theadvantage is thereby obtained that the machine can be operated either bythe standard control, supplied by the main control valve with the timermechanism and rest interval timing piston or by the auxiliary control.

It is advantageous if the main control valve spool has means, operatedby a hand lever, for locking it in the position which it occupies whenthe electromagnet for operating it is energized; thus has the advantagethat the electromagnet is not energized while the auxiliary control isbeing used.

Obviously, changes can be made in the arrangement of lines, controlvalves and cocks; thus for example both control valves can be installedin the discharge line.

The subject matter of the invention is shown in several exemplaryembodiments in the drawings, in which Figure 1 shows an overall controlplan,

Figures 2 and 3 show embodiments of the control means,

Figure 2a is a schematic showing of the electrical circuit of theapparatus of Figure 2,

Figures 4 and 5 are transverse sections taken along line 4-4 and 55,respectively, of Figure 3; and

Figure 6 is a view similar to Figures 4 and 5 of a modified valve.

In Fig. 1, 1 and 2 denote the threading rolls, of which the roll 1 isstationarily journalled and the roll 2 is journalled on the slide 3,which is movable by the operating pistons 4 in opposition to theretracting spring 5. The cylinder block for both pistons 4 is designatedby 6. The work rest 7 with the work piece 8 to be rolled is disposedbetween the threading rolls. The threading rolls are driven by thedriving motor 15 through the gear box 14, shaft 13, worms 11, wormwheels 12 and drive shafts 9 and 10.

The shaft 16 branches off from the transmission 14, runs at the samerotational speed as the operating shafts 9, and is connected to thevariable speed transmission 17 which is variable as infinitely aspossible by means of the handle 18. This transmission has two driveshafts 19 and 20 which operate the control valves 21 and 22, with theaid of the disc cams 23 and 24. The control valves are installed in thehydraulic circuit, not shown in this diagram, of the operating pistons 4and control the full or metered flow of hydraulic fluid to the pistonsand the discharge therefrom. The movement of the threading rolls 1 and 2toward or away from each other and the threading path traveled throughon these cylindrical threading rolls is therefore adjustable to thespeed of the threading rolls, depending upon the rotational speed ratioset at the transmission 17.

One embodiment of this control is shown in Fig. 2. The two operatingcylinders for the movable slide, not shown, which carries a threadingroll, movable toward the other threading roll, areas in Fig. ldesignatedby 6 and the operating pistons by 4. The main control valve spool 25 isinstalled in the pressure line 27 from the pump 26. The feed regulatingvalve 28 is located in the branch line 29 of the line 27. The branchline 29 leads to the control valve spool 30 for the rapid infeed. Thesecond feed regulating valve 32 is installed in the branch line 31. Bothlines 29 and 31 lead through the valve spool 30 and in such a way that,in the end position of the spool, the metered line 31 is connected tothrough-flow while the line 29 is closed. Beyond the valve spool 30, thelines 29 and 31 join line 33 which empties into the cylinder block 6 andwhich contains the cock 34. .The cock 35 is installed in line 29 aheadof the valve spool 30 and ahead of this cock the line 36 branches oiland likewise leads to the cylinder block 6. Two drain lines 37 and 38lead from the spool of valve 22 to the reservoir 39. The spring 40 urgesthe valve spool 30 with the push rod 41 against the cam 24 which isdriven by the variable speed transmission 17. The transmission 17 ismaintained in driving connection with the driving motor 15 (Fig. 1) forrotating the threading rolls.

The pressure regulating valve 43 is associated with the main valve spool25 and is installed in the branch line 44 of pressure line 27 which isalso closed at the relief valve 45. The pressure regulating valve 43 andrelief valve 45 have discharge lines 46 and 47 which empty into thereservoir 39. A resetting spring 48 normally urges the valve 25 to theleft as viewed in Figure l and an electromagnet 49, when energized,opposes the spring to move the valve to the position shown in Figure 2.By means of the manual control handle 50, which has the latch means 51,the main valve spool 25 may be moved into the position shown and lockedtherein when it is to be disconnected. The body of the main valve spool25 has, at both ends, drain lines 52 and 53, as well as the dischargeline 54, which is controlled by the main valve spool 25. The dischargeline 54 is closed when the spool is actuated by the electromagnet 49 orlatched. Therefore the line 54, which is connected to the cylinder 6, isunder pressure. In the branch line 55 are installed the pressureregulating valve 56 and the timer piston 57 for regulating the restinterval, which closes the contacts 58 and 59 when the piston 57 movesback under pressure of the spring 60 when the lines 54 and 54' areconnected to open discharge. The contacts 58 and 59 close the circuitfor the electromagnet 49, in which circuit the switch 61 is disposed.Switch 61, when opened, breaks the circuit through contacts 58 and 59.The switch 61 is closed when the rest interval regulator is inoperation. This is indicated by the control lamp 62. The drain line 63is connected to the cylinder of the timer piston 57. The cock 65, whichserves to bleed the air, is installed in the line 64 which branches oilfrom the line 54'. The line 64 leads to the reservoir 39.

The cock 67 and the valve 21 having the valve spool 69 for controllingthe rapid reciprocation of the threading rolls are installed in thedischarge line 66 leading from the cylinder 6. The re-setting spring isdenoted by 70. This spring urges the push rod 71 of the valve spoolagainst the cam 23 which is driven by the transmission 17 and which isarranged in fixed phase with the cam 24. In the position shown thedischarge line 66 is opened by the valve spool 69. The valve 21 isprovided with the drain line 73. The timer device 74 operates to stopthe rolling operation by de-energizing the solenoid 49.

The timer assembly 74 which may be of conventional construction includesa motor driven timer element effective to close the circuit to theopening solenoid 92 of normally closed switch 94 a predetermined timeafter the timer power circuit including power lines 96 and 97; isenergized by closing of the normally open pressure operated switch 98.The switch 98, which is normally open, is closed by the application ofpressure through conduit 99 connected to cylinders 6. The switch 94 ispositioned in a simple holding circuit in parallel with the restinterval contacts 58 and '59, the holding circuit also including anormally open switch 100 closed by a solenoid 102, the switch 139 beingin series with the by the latch 51. -rneans is disconnected and'theauxiliary controllrn s aaaaeaa In this manner the normal controlfor'automatic reciprocation is connected.

the line 29 leads directly to the cylinder block 6. The

rotary valves .75 and 76, which correspond to the valve Spools '69 and30, are installed in'the discharge line 66. The rotary valves 75 and 76are driven via the transmission 17 as shown in 'Fig. 1. The rotary valve75 is installed in the branch line 66a and the rotary valve 76 in thebranch line 66b. The cocks 77 and 78 are disposed in branch line 66abefore and behind therotary valve 75 and the cocks 79 and 36 aredisposed in branch line 66b before and behind the rotary valve 76. 7 Thevalve 75 serves to cause rapid reciprocation of the threading'rolls andhas the recess .81, as is evident from Fig. '4, which shows a crosssection through valve 75 along line 44. The cross section through thevalve 76 along line 5-5 is shown in Figs. 5 and 6 which illus- 'trateexemplary embodiments of this rotary valve. "The valve '75 has on itscircumference the shallow, arcuately rising recess 82, which extendsover the arc x. The adjacent cylindrical portion 83 extends over the arcy. The arcuately rising recess 84, which extends over the are z, adjoinsthe cylindrical portion. In the other modification .of rotary valve 76ashown in Fig. 6, the recess 85, which permits the free discharge, isprovided in addition to the recesses 82 and84. V

The manner of operation of the embodiment illustrated in Figure Z'Wlththe auxiliary control apparatus disconnected by disposing the valves 34,35, and '67, in the dotted line positions of Figure 2 will now bedescribed. Assuming that the pump 26 is in' operation, that the drivemotor is energized to. rotate the rolls and that the switch 61 is open,rolls will be fully retracted because of the connection of dischargelines 54 and 54'. When switch 61 is closed, the solenoid 49 will beenergiz ed by reason of the fact that switch contacts 58 and 59 are alsoconnected thus moving the valve to the position shown in Figure 2closing the discharge line thereby establishing pressure in cylinders 6.When switch 61 is closed solenoid 102 will be energized thus closing theswitch100. As soon as rolling pressure is established the contacts 58and .59 will be opened and the switch 98 will be closed energizing thetimer mechanism 90. After a pre-set time interval the timer mechanism 90will energize the solenoid 92, thereby opening the switch 94 tode-energize 49 and connect the discharge lines 54 and 54' and permit theretraction of the rolls. This action also opens switches 98 and 190 andsolenoid 49 will remain de-energized until the switch contacts 58 and 59are again connected after the interval established by the setting ofregulating valve 56. During the rolling action the speed at which theroll 2 is advanced toward the roll 1 is determined by the setting of thefeed regulating valve 28.

To connect the auxiliary control means, the cocks 34, and 67 are movedto the positions I shown in full lines. Furthermore, the feed regulatingvalve 28 at the main control panel is opened fully, so that regulationof the feed is now effected by the second feed regulating valve 32. Alsothe main valve spool 25 is moved by the handle into the position shownwhile the electromagnet 49 is deenergized; it is locked in this position\Vhen large work pieces are being rolled, .therapid ,infeed of threadingrolls 1 and 2 ,is effected by the valve 'The valve spool 69 has openedthe discharge line 66 fully, so that the hydraulic fluidflows out of thecylinder .6. After the resultant return movement the valve spool 69 ismoved by the rotating cam 23 into the dotted-line position, in which thedischarge line 66 is closed. The valve spool 30 is still in thefull-line position. From this moment on, the hydraulic fluid deliveredby the pump 26 reaches the cylinder 6 through the fully opened feedregulating valve 28, line 29, the line 31 metered by the second feedregulating valve 32, the valve spool 30 and line 33, so that the slide 3of the threading rolls '1 and 2 begins its infeed movement. In' the nextinstant the rotating cam 24 moves the valve spool 30 into the dottedlineposition in which the unmetered line 29 is opened so that the fullvolume of oil passes through line 33 to the operating cylinder.The-rapid infeed'takes place and is maintained until the threading roll2 touches the work piece 8. At this instant the push rod 41 of the valvespool runs off of the 'cam 24 so that the valve spool is again disposedin the full-line position. The line is 'agairi'close d and the-feedof'the threading roll is etfected via the metered line 31 in accordancewith the amount of metering set at the feed regulating val-ve 3'2. Afterthe rolls 1 and 2 have completed -a pre-determ-ined number ofrevolutions, the valve spool 69 again opens the discharge line and theprocess repeats. During the separating movement of the threading rolls,the finishrolled work piece is carried away and a work piece to berolled is fed by means of known automatically operating transfermechanisms. I

To connect the circuit for rapid reciprocating movement of the threadingrolls the cocks 34 and 35 are placed in the dotted-line positions II.The cock 67 remains in position I. Thereby the valve spool 30 for therapid infeed is disconnected and only the valve spool 69 operates. Themain valve spool 25 is in the locked position. The feed regulating valve28 at the main valve spool is adjusted to the amount of meteringdesired.

The hydraulic fluid delivered by the pump 26 passes, through the feedregulating valve 28, line 29, line 36 and the cock 35 which is open tothis line to the operating cylinder 6. With the discharge line 66closed, the pressure builds up and rolling of the work piece iseffected. But if the discharge line 66 is opened by the cam 23 being inthe appropriate position, the hydraulic fluid flows freely out of theoperating cylinder 6 through the discharge line 66. Thereupon theprocess repeats. the speed of the cam 72 may be regulated by thetransmission 17, relative to the speed of the threading rolls 1 and 2,the reciprocating movement of the threading rolls and therewith therolling travel may be altered as desired.

The manner of operation of the embodiment with rotary valves shown inFigs. 3 through 6 is the same in principle as that of Fig. 2. Thedifference is merely that the cams 23 and 24 are eliminated, sothat therotary valves 75 and 76 are driven directly from the transmis-' sion andfurther that both rotary valves are installed in the discharge line. Itis possible for both rotary valves to cooperate, as is the case in Fig.2. In this case the valve 76 controls the smooth start of the rapidinfeed by the recess 82, the rapid infeed itself by the circumferentialportion 83, the start of the feeding movement by the recess '84 and theremaining portion of the rotary valve circumference, while the dischargeis effected by the rotary valve 75 and its recess 81. For this pur;

Since,

pose the rotary valves 75 and 76 must operate in synchronism, as is alsothe case in the embodiment of Fig. 2.

When the cocks 79 and 80 are closed, the rotary valve 76 for the rapidinfeed is disconnected and the valve 75 operates alone to control therapid oscillation of the slide 3 of the threading roll 2.

However, it is also possible to effect free discharge at the valve 76 bythe recess 85, so that, in this case, this valve controls all movementsof the threading rolls. In this case the cocks 77 and 78 are closed.

When all cocks 77 through 80 are closed, the thread rolling machineoperates only with the already discussed main control means and withoutthe auxiliary control.

However, the auxiliary control can also operate as the main control whenit is a question of a thread rolling machine for fully automaticoperation. In this case the previous main control box with timermechanism and rest interval timing piston is eliminated and instead ofit, the rolling pressure regulating valve 43, relief valve 45 and thebleeder cock 65 are admitted into the control system.

We claim:

1. In a roll forming apparatus, a pair of rolls, means mounting one ofsaid rolls for movement toward and away from the other of said rolls,means for rotating said rolls, a fluid pressure piston for moving saidone of said rolls, pressure and exhaust conduits connected to saidpiston, a pluralityof valves arranged in parallel in said exhaustconduit, separate operators for each of said valves, and meansmechanically connecting the means for rotating said rolls and each ofsaid valve operators for actuating each of said valve operators in timedrelation with the rotation of said rolls.

2. In a roll forming apparatus, a pair of rolls, means mounting one ofsaid rolls for movement toward and away from the other of said rolls,means for rotating said rolls, a fluid piston for moving said one ofsaid rolls, pressure and exhaust conduits connected to said piston,valves in each of said conduits, said valves having spools provided withcam followers, cam means for engaging said cam followers to move saidvalve spools, and a variable speed drive transmission drivinglyconnecting said cams to said means for rotating said rolls for operatingsaid cams and said valves in timed relation with the rotation of saidrolls.

3. In a-roll forming apparatus, a pair of rolls, means mounting one ofsaid rolls for movement toward and away from the other of said rolls,means for rotating said rolls, a fluid piston for moving said one ofsaid rolls, pressure and exhaust conduits connected to said piston, avalve in said pressure conduit having at least two parallel fluidpassages, control means for selectively closing one of said passages topermit the supply of fluid to said piston at a relatively reduced rate,means to operate said control means in timed relation with the rotationof said rolls, a by-pass circuit in said pressure conduit across saidvalve adapted to permit flow of fluid to said piston at a predeterminedrate, and valve means for selectively directing fluid to said pistonthrough said by-pass circuit or through said valve.

4. In a roll forming apparatus, a pair of forming rolls, means mountingone of said rolls for movement toward and away from the other of saidrolls, means for rotating said rolls, a fluid piston for moving said oneof said rolls toward and away from the other of said rolls, pressure andexhaust conduits connected to said piston, means resiliently urging saidone of said rolls away from said other of said rolls, valve means insaid conduits having first, second and third relative operatingpositions effective, respectively, to move said one roll toward saidother roll at a first rate, to move said one roll toward said other rollat a second lower rate and to permit the retraction of said roll underthe influence of said resilient means, and a mechanical drive connectionbe tween said means for rotating said rolls and said valve means formoving said valves to said first, second and third relative operating intimed relation with the rotation of said rolls.

5. The combination according to claim 4 wherein said valve means isprovided with cam followers and said last mentioned mechanical driveconnection includes cams for engaging said cam followers and a variablespeed drive transmission drivingly connecting said cams to said meansfor rotating said rolls.

6. The combination according to claim 4 wherein said valve meansincludes rotary valves and said mechanical drive connection includes avariable speed drive transmission drivingly connecting said rotaryvalves to said means for rotating said rolls.

7. In a roll forming apparatus, a pair of forming rolls, means mountingone of said rolls for movement toward and away from the other of saidrolls, means for rotating said rolls, a fluid pressure piston for movingsaid one of said rolls toward and away from the other of said rolls,pressure and exhaust conduits connected to said piston, a pair of rotaryvalves arranged in parallel in said exhaust conduit, and a variablespeed drive transmission drivingly connecting said rotary valves to themeans for rotating said rolls for operating said valves in timedrelation wtih the rotation of said rolls.

8. -In roll forming apparatus, a pair of rolls, means mounting one ofsaid rolls for movement toward and away from the other of said rolls,means for rotating said rolls, a fluid piston for moving one of saidrolls, pressure and exhaust conduits connected to said piston, valvemeans in one of said conduits having at least two fluid passages, meansfor selectively closing one of said passages to reduce the rate of flowof fluid through said one conduit, additional valve means in the otherconduit, and means mechanically driven by said means for rotating saidrolls for actuating said valves in timed relation with the rotation ofsaid rolls.

9. In a roll forming apparatus, a pair of rolls, means mounting one ofsaid rolls for movement toward and away from the other of said rolls,means for rotating said rolls, a fluid pressure piston for moving saidone of said rolls, pressure and exhaust conduits connected to saidpiston, a valve in at least one of said conduits, an operator for saidvalve, valve control means operatively associated with said operator,and means drivingly connecting said means for rotating said rolls tosaid valve control means adapted to operate said valve in synchronousrelation with the rotation of said rolls.

10. In a roll forming apparatus, a pair of rolls, means mounting one ofsaid rolls for movement toward and away from the other of said rolls,means for rotating said rolls, a fluid pressure piston for moving saidone of said rolls, pressure and exhaust conduits connected to saidpiston, a valve in each of said conduits for controlling the flow offluid therethrough, a separate operator for each of said valves, valvecontrol means operatively associated with each of said valve operators,and means drivingly connecting said means for rotating said rolls tosaid valve control means adapted to operate said valves in synchronousrelation with the rotation of said rolls.

References Cited in the file of this patent UNITED STATES PATENTS1,764,099 Galloway June 17, 1930 1,780,471 Galloway Nov. 4, 19301,920,596 Schafer Aug. 1, 1933 2,257,253 Wemhoner Sept. 30, 19412,624,218 Flanders et al. Jan. 6, 1953 FOREIGN PATENTS 254,315Switzerland Apr. 30, 1948 256,890 Switzerland Sept. 15, 1948 235,330Germany Apr. 3, 1945

